Berries

Unlike with mushrooms, it is easier to identify which kind of berries are edible. There is a "berry rule" to simplify the process of determining if a berries are edible. White and yellow berries are a no go as 90% of them are inedible. Red berries are a much safer bet with a 50/50 chance of them being edible. A safer alternative would be blue, black, or purple berries as 90% of them are edible. The only truly safe berries would be aggregated berries with almost 100% (~99%) of them being edible. Without going too in depth aggregated berries are berries made up of multiple little components. A few examples would be raspberries, blackberries, and strawberries. Strawberries are considered aggregated because those seeds that surround them aren't actually seeds but little fruits. To further confirm if a berry is safe (if it isn't aggregated) avoid berries on plants with spines, bitter smells, or milky sap. You can also check if the berry juice aggravates your skin. And once you do decide to eat them, only start with one. See how your body reacts and if it tastes bad, it might be poisonous (or just unripe).

Weirdly enough the study of blackberries is called batology. Another interesting aspect about blackberries is how they are red before they ripen unlike the usual green.

If you're ever had a really bad headache before, you might have tried to check online for a trick to lessen the pain. One of these methods happens to be eating strawberries as they contain salicylates, an ingredient found in aspirins.

Raspberries can come in all sorts of colors and golden raspberries are the sweetest of them all. Some other colors would be purple and black (also red). They also don't continue to ripen after they are picked. Thus unlike fruits like bananas, they aren't picked in advance and need to be sold asap.

You can also use berries as natural dyes. The most commonly used seem to be blueberries.